ECU and TCU arguing? Topic is solved

greg850r · Post by **greg850r** » 22 Oct 2016, 04:18

Hi all,
I just swapped the engine and trans out of a wrecked 96 Turbo sedan into a 95 Turbo wagon (complete cradle). The issue is it seems to go into limp mode after 10-20 miles. The only symptom otherwise is flat throttle response when pushed that's worse than just the turbo not spooling up. I've tried the brains from both the 96 and the 95 with the same result. The dash indicators are giving me an alternating flash pattern between the arrow and the check engine light even when it drives normally in the beginning. The only wiring change I made was to the speed sensor on the trans as it is on the rear of the 95 trans and on the top of the 96. The plugs are different so I had to splice the 96 one into the 95's wiring to plug things up. If any of you guys understand the computer functions better than I do some suggestions would be a great help. Thanks.

Post by **tryingbe** » 22 Oct 2016, 06:08

No, you don't splice the wires there.

You take the transmission speedo wire from the 95 and you spice it to the ABS sensor at the driver side. You may add wires, and be sure to match up the ground with the ground.

http://volvospeed.com/vs_forum/topic/14 ... or-wiring/

greg850r · Post by **greg850r** » 30 Oct 2016, 14:01

That did it. Got a speedo and car drove well with original 95 TCU & ECU. Still flat turbo response when hot but boosts ok cold. Son drove for a couple days with no issues then it came home in limp mode again, To be clear, now the sensor on top the trans is not connected to anything.
Even though it's a 95 it does have an OBD2 port so I checked and it threw a code P1418 Fuel level sensor circuit signal too high.
Took it for a drive just now (2 miles). Drives well when boost gauge in negative territory but as soon as it shows boost power goes away. Floor it and hold it there and it shows boost but barely maintains speed as soon as I back off throttle it starts to pull. Starting to wonder about vacuum hoses. I already know there is no EGR under intake anymore and that controller on top the radiator should probably be dealt with.

Post by **tryingbe** » 30 Oct 2016, 14:53

It's a 95, get the OBD I code.It's more useful.
https://www.matthewsvolvosite.com/read-codes-volvo-850